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Seasonal Climate Outlook

Summary

The Department of Primary Industries and Regional Development’s (DPIRD) Statistical Seasonal Forecast (SSF) system for January to February 2019 is indicating mixed chances of exceeding median rainfall for the South West Land Division (SWLD). Due to the current US Government shutdown, data sets from NOOA (necessary for the calculated of the SSF) cannot be accessed, therefore the SSF is unable to be updated to include a March forecast.

For January to February 2019, the SSF is indicating for above 60% chance of exceeding median rainfall for the far northern grainbelt, below 40% chance of exceeding median rainfall for south-eastern and Esperance shires and neutral chance elsewhere. The most probable decile range is decile 4-7 for most of the grainbelt and decile 8-9 for far northern grainbelt and Albany. Predictive skill based on November conditions is mostly poor to good (50- 70% consistent).

The Bureau of Meteorology’s current seasonal outlook is indicating less than 40% chance of exceeding median rainfall for January to March 2019 for the SWLD. Predictive skill is poor to moderate (45-65% consistent).

Temperature outlooks for January to March 2019 from the Bureau indicate 50-75% chance of above average day-time maxima for the SWLD. Skill is moderate to good at 55-75% consistent. Minimum temperature outlooks indicate 30-60% chance of above average night-time minima (lower chances along the coast), with skill mostly moderate at 50-65% consistent.

December rainfall was generally average in the SWLD. December maximum temperatures were average to above average and minimum temperatures were average.

It is important to note that historically, SWLD January and February rainfall is usually very low. However, localised and quick forming thunderstorms can bring heavy rainfall and statistical and dynamical climate forecasts can miss these weather systems.

Three month outlook for the south-west of Western Australia

Statistical Seasonal Forecasting (SSF)

DPIRD’s SSF system uses historical relationships between global sea surface temperature and sea level pressure with rainfall in south-west Australia to produce forecasts of rainfall for the coming months. Users can click on any station indicated on the map for location-specific forecast information from the Seasonal Climate Information page. Currently there is no climate data coming from NOAA and the SSF can’t be updated.

For January to February 2019, the SSF is indicating for above 60% chance of exceeding median rainfall for the far northern grainbelt, below 40% chance for south-eastern and Esperance shires and neutral chance elsewhere. The most probable decile range is decile 4-7 for most of the grainbelt and decile 8-9 for far northern grainbelt and Albany. Predictive skill based on November conditions is mostly poor to good (50-70% consistent).

SSF forecast of the probability of exceeding median rainfall for January to February 2019 using data up to and including November

Percent Consistent skill of the SSF at forecasting January to February rainfall using data up to and including November